+---Richard Trethewy (ABT 1665-JAN 1741)
+---John Trethewey (ABT 1690-)
| +---Ann Martyn 
(ABT 1666-JUN 1738)
+---Joseph Trethewy (ABT 1735-DEC 1816)
| | +---Phillip Mellow (ABT 1660-JAN 1711)
| +---Temperance Mellow (ABT 1690-MAY 1765)
| +---Jane ?
+---John Trethewey (ABT 1764-JAN 1834)
| | +---John Rickard
| | +---Jonas Rickard (ABT 1705-)
| +---Caroline Rickard (ABT 1734-)
| +---Honour ?
+---Joseph Trethewey (ABT 1793-)
| +---Charity Strangeman (1756-)
+---John Trethewey (ABT 1817-1890)
| | +---Benjamin Warrick
| +---Elizabeth Warrick (ABT 1788-)
| +---Jenifer ?
+---Thomas (Tom) Trethewey (ABT 1858-21 JUN 1910)
| | +---Richard Hicks
| +---Ann Hicks (ABT 1820-)
| +---Philadelphia ?
Hannah Trethewey (31 MAR 1883-)
| +---James Hibberd (ABT 1829-)
+---Rose Caroline Hibberd (10 DEC 1860-09 OCT 1915)